Can anyone help me and name a few? I am open to fighters today but especially fighters of the past. Thanks.
Flash Elorde, he was intentionally converted to southpaw stance because his trainer believed there is a stylistic advantage to being one. Paul Spadafora was converted to southpaw by accident, literally. He got shot in the right leg, and he found it badly weakened which affected his orthodox stance. He switched.
oscar is a natural lefty and would occasionally swtich in fights same with MAB (as recently discovered here)
Ayub Kalule watched his southpaw older box and thought that is was the way to box. That is why he had a great righthand jab and hook, but no left cross to speak about. (although Ho Joo from Corea would beg to differ) Woller
Roy Jones switched to southpaw every now and then. Naseem Hamed switched stances often. Marvin Hagler was known for doing this. Mayweather has done it. Andre Ward is another one.
Rodolfo Martinez comes to mind. He was a converted southpaw but would switch lefty when he needed it. In his bout against Venice Borkorsor, he was being schooled for the first 4 rounds, then switched lefty and controlled the bout from there on. I believe he did the same in his bout with Mike Ayala, but I would need to research that one.
Cotto, Tyson and yes as mentioned before Franky Bruno tried it in the rematch with tyson. The commentators stated he was going to get clobbered even more because of that